Now I add new node field in to form template, then upload to sharepoint.
When I open old form, that hasn't new node field, the error is occured.
Thank you very much.
Iam not sure the following will work. but try this out.
1. Open the form in design mode.
2.Go to Tools->Form Options-> Versioning.
3. Select 'Automatically Upgrade existing forms ' in On version upgrade drop down.
4. Publish the form.
Thanks a lot. I can try it. ^ ^